1. Field of Invention
The present invention relates to a method for reducing computational complexity of video compression standard, and more particularly to a spatial correlation based method for reducing computational complexity of video compression standard.
2. Description of Related Art
H.264/AVC (Advanced Video Coding) is the video compression standard established by the Joint Video Team (JVT) consisting of the Video Coding Experts Group (VCEG) of ITU-T and the Moving Picture Experts Group (MPEG) of International Organization for Standardization (ISO)/International Electrotechnical Commission (IEC). The term of H.264 is named on the basis of the series of H.26x by ITU-T, and AVC is the appellation of ISO/IEC MPEG. The final draft of first edition for this standard is admitted in May of 2003.
The initial objective of establishing H.264/AVC is to provide a higher compression rate on video quality than prior related art (such as MPEG-2 and H.263), and to diminish some complex coding/decoding implements in order to simplify the hardware. Moreover, another objective is the adaptability for the video compression standard to be used in extensive range (including the video of high bit or low bit and different video resolution), and applicable to various networks or systems (such as the multi-media mobile phone system or the high-density television) The H.264/AVC intra coding system can be divided into some primary parts including the intra prediction, the transformation and quantification (DCT/Q/IQ/IDCT), the context adaptive variable length coding (CAVLC) and the mode decision. Due to the Intra prediction needs to generate thirteen kinds of predictors for luma (Luminance) and four kinds of predictors for chroma, this parts of the intra prediction and the mode decision take almost 70% computation for intra coding during the image-frame coding process.
In order to compute minimal rate-distortion cost, each kind of predictors would do subtraction with the original pixel, be transformed by two-dimensional Hadamard and sum up the transformed factors to determine the best prediction mode. Reducing the computation of prediction mode would speed up the performance of the intra coding system but would also affect image quality. Therefore, the present invention supplies a method to reduce the computation of prediction mode with a little deterioration of image quality.